Modern vehicles such as automobiles include multiple control systems that regulate the operation of various components of the vehicle. In many cases, the control systems use input data from one or more sensors. The sensors provide data that is used to optimize the vehicle's operation. As the number of control systems increases and as the control systems themselves become more complex, additional sensors are often used to provide additional data to the control systems. However, the inclusion of additional sensors to the vehicle adds to the vehicle's complexity and cost.
One vehicle system that uses sensors for data input is the vehicle's powertrain and associated control system. The powertrain in a motor vehicle refers to the group of components that generate and deliver power to a road surface. The powertrain generally includes the motor vehicle's engine and transmission. Other vehicle components such as the vehicle's driveshafts, differentials and drive wheels may also be grouped as part of the powertrain. The powertrain is controlled using a control system. The control system ensures that the powertrain generates a desired power (for example, to propel a vehicle forward along a level surface). Optimal control of the powertrain, however, requires knowledge of the vehicle's mass, among other factors. For instance, knowledge of the vehicle's mass is necessary to determine how to modify a “driving strategy.” Driving strategy dictates shift pattern (or when to shift gears of the vehicle) and is compensated by knowledge of the vehicle's mass.
Because a vehicle's mass can dramatically change during operation of the vehicle, optimum operation of the vehicle's powertrain requires that the vehicle's mass be frequently determined. For example, in a commercial vehicle, a fully loaded vehicle could have a mass that is as much as three times the mass of the unloaded vehicle. Non-commercial vehicles also change mass as a result of loading and unloading, hitching trailers and other accessories that add to or otherwise change the total mass being driven by the vehicle's powertrain.
In order to dynamically measure a vehicle's mass and provide input to the vehicle's powertrain, some commercial vehicles include one or more mass detection sensors. These sensors are designed specifically to determine the vehicle's mass, and, as an extra component, add to the overall cost and complexity of the vehicle. Perhaps because of this additional cost, non-commercial vehicles generally do not utilize the additional mass detection sensors. Instead, an approximate mass value for the vehicle is used as a constant, non-changing input to powertrain calculations. While this reduces initial cost and complexity, the use of the constant mass value regardless of changes in the vehicle's mass results in sub-optimal control of the vehicle's powertrain.
There exists, then, a need and a desire for a system capable of dynamically calculating a vehicle's mass and other characteristics without using additional mass detection sensors.